The synthesis of natural products (e.g., eriolanin, eriolangin, helenalin, elephantopin, bruceantin) and analogs (6-epi-eriolangin, deoxyelephantopin, deoxyvernolepin, A-norbruceantin (138)) which are known to possess structural features (alpha, beta-unsaturated carbonyls) responsible for tumor inhibitory activities are planned. The development of new methods in organoselenium chemistry for application to the syntheses of the above named natural products and analogs will be undertaken. The various compounds synthesized will permit in vivo testing as well as allow further structure-activity relationship studies to continue. It is hoped that the various substrates encountered during this study will exhibit selective toxicity against neoplastic cells to be of chemotherapeutic value.